Systems and methods for selective proximity cobalt recovery

ABSTRACT

Various embodiments provide a method comprising leaching a cobalt bearing material to form a slurry, filtering the slurry to yield solids and a cobalt bearing liquid phase, and forwarding the solids to a second leaching operation.

FIELD OF INVENTION

The present invention relates, generally, to systems and methods forrecovering metal values from metal-bearing materials, and morespecifically, to systems and methods for recovering cobalt and othermetal values.

BACKGROUND OF THE INVENTION

Cobalt is an industrially important element that may be used in variouscatalysts, dyes, alloys, inks, battery additives, and other industriallybeneficial products. Cobalt may be found in nature in a variety of formsand in a variety of ores. Cobalt containing ores include cobaltite,heterogenite (CoOOH), erythrite, glaucodot, and skutterudite. As foundin nature, cobalt often exists in an oxidation state other than zero.For example, cobalt is often found in the form of cobalt II and cobaltIII. Cobalt metal is commercially saleable, though purified forms ofcobalt II and/or cobalt III, such as those in a salt form, are alsocommercially saleable.

In conventional processes, cobalt containing materials precipitated withmagnesium oxide (MgO) and subsequently leached tend to be difficult tofilter. In addition, large volumes of aqueous solution are typicallyemployed. More efficient systems and methods for cobalt recovery wouldbe commercially and industrially advantageous. In addition, it would becommercially and industrially advantageous to produce both cobalt metaland ionic cobalt.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides systems and methods formetal value recovery, such as cobalt recovery. In various embodiments, amethod is provided comprising leaching a cobalt bearing material to forma slurry, filtering the slurry to yield solids and a cobalt bearingliquid phase, and forwarding the solids to a second leaching operation.

In various embodiments, a method is provided comprising adding magnesiato a cobalt bearing material to form a first slurry, separating thefirst slurry into a saleable solid product and a liquid phase, addinglime to the liquid phase to form a second slurry, and separating thesecond slurry into a solid product and a liquid phase.

Further areas of applicability will become apparent from the detaileddescription provided herein. It should be understood that thedescription and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the present invention is particularly pointed outand distinctly claimed in the concluding portion of the specification. Amore complete understanding of the present invention, however, may bestbe obtained by referring to the detailed description and claims whenconsidered in connection with the drawing figures, wherein like numeralsdenote like elements and wherein:

FIG. 1 is a flow diagram illustrating an exemplary process in accordancewith various embodiments of the present invention;

FIG. 2 is a flow diagram illustrating an exemplary process, including aleach process, in accordance with various embodiments of the presentinvention;

FIG. 3 is a flow diagram illustrating an exemplary process, including aprimary metal recovery process, in accordance with various embodimentsof the present invention;

FIG. 4 is a flow diagram illustrating an exemplary process, including aprimary metal recovery process, in accordance with various embodimentsof the present invention;

FIG. 5 is a flow diagram illustrating an exemplary process, conductednot in close proximity to a primary metal recovery process, inaccordance with various embodiments of the present invention; and

FIG. 6 is a flow diagram illustrating an exemplary process, conductednot in close proximity to a primary metal recovery process, inaccordance with various embodiments of the present invention.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present invention, its applications, or its uses.It should be understood that throughout the drawings, correspondingreference numerals indicate like or corresponding parts and features.The description of specific examples indicated in various embodiments ofthe present invention are intended for purposes of illustration only andare not intended to limit the scope of the invention disclosed herein.Moreover, recitation of multiple embodiments having stated features isnot intended to exclude other embodiments having additional features orother embodiments incorporating different combinations of the statedfeatures.

Furthermore, the detailed description of various embodiments hereinmakes reference to the accompanying drawing figures, which show variousembodiments by way of illustration. While the embodiments are describedin sufficient detail to enable those skilled in the art to practice theinvention, it should be understood that other embodiments may berealized and that logical and mechanical changes may be made withoutdeparting from the spirit and scope of the present invention. Thus, thedetailed description herein is presented for purposes of illustrationonly and not of limitation. For example, steps or functions recited indescriptions any method, system, or process, may be executed in anyorder and are not limited to the order presented. Moreover, any of thestep or functions thereof may be outsourced to or performed by one ormore third parties. Furthermore, any reference to singular includesplural embodiments, and any reference to more than one component mayinclude a singular embodiment.

The present invention relates, generally, to systems and methods forrecovering metal values from metal-bearing materials, and morespecifically, to systems and methods for selective proximity recovery ofcobalt. Various embodiments of the present invention provide a processfor recovering cobalt that varies in accordance with, among otherthings, proximity to a primary metal value recovery operation. Invarious embodiments, it has been discovered that various methodologiesof cobalt recovery may be used to advantageously affect the recovery ofa primary metal value. Moreover, in various embodiments, it has beendiscovered that various methodologies of cobalt recovery may be used toadvantageously improve the recovery of cobalt, for example, inoperations that are not in close proximity to a primary metal valuerecovery operation.

Metal values such as, for example, copper, gold, silver, zinc, platinumgroup metals, nickel, cobalt, molybdenum, rhenium, uranium, rare earthmetals, and the like, may be recovered from metal-bearing materials inaccordance with various embodiments of the present invention. A primarymetal value may refer to a metal value that is recovered from ametal-bearing material. A secondary metal value (and tertiary metalvalues, etc) may also be obtained from the metal-bearing material. Whileany metal value may be deemed to be a primary metal value, typically aprimary metal value will be present in the metal-bearing material in agreater concentration than a secondary metal value. For example, invarious embodiments, copper may be considered a primary metal value andcobalt may be considered a secondary metal value.

A primary metal value recovery operation may refer to any metal valuerecovery operation that seeks to recover a primary metal value. Forexample, a primary metal value recovery operation may include a leachingoperation (e.g., a primary metal leach) that produces a pregnant leachstream containing a primary metal value.

A primary metal value recovery operation may be operated in closeproximity to a cobalt recovery operation. Close proximity refers to adistance within which it would be reasonable to transport metal valuebearing materials between the primary metal value recovery operation andthe cobalt recovery operation. For example, close proximity may refer toa portion of the primary metal value recovery operation existing within50 km of the cobalt recovery operation, within 25 km of the cobaltrecovery operation, and within 5 km or fewer of the cobalt recoveryoperation.

It has been discovered that cobalt may be recovered using a bagged anodeelectrowinning process, which may be advantageous where a primary metalvalue recovery operation is operated not in close proximity to a cobaltrecovery operation. It has also been discovered that cobalt may berecovered using electrodes that are not sequestered, which may beadvantageous where a primary metal value recovery operation is operatedin close proximity to a cobalt recovery operation.

In various embodiments, a primary metal value recovery operationoperated in close proximity to a cobalt recovery operation may receiveone or more output streams from the cobalt recovery operation. Suchoutput stream may contain the primary metal, enhancing recovery of theprimary metal value. Moreover, in such a manner, media (e.g., acid)and/or reagents may be conserved.

With reference to FIG. 1, a metal recovery process 100 is illustratedaccording to various embodiments of the present invention. Metalrecovery process 100 may be performed in close proximity to a primarymetal value recovery operation. Metal recovery process 100 comprisessubjecting cobalt bearing material (“Co MAT”) 102 to reactive process104, filtration 106, and conditioning 108. At least a portion of thetails of filtration 106 may proceed to primary leaching 120. A firstportion of the output of conditioning 108 is sent to precipitation andfiltration 112 and a second portion of the output of conditioning 108 issent to further processing 110 to yield cobalt metal.

Cobalt bearing material 102 may be an ore (cobaltite, heterogenite(CoOOH), erythrite, glaucodot, skutterudite, other cobalt containingores, and mixtures of cobalt containing ores with ores bearing othermetal values), a concentrate, a process residue, an impure metal salt, apreprocessed cobalt bearing material, combinations thereof, or any othermaterial from which cobalt values are present. Cobalt, whether in metalor ionic form, may be recovered from cobalt bearing material 102 inaccordance with various embodiments of the present invention. In variousembodiments, cobalt bearing material 102 contains other metal values,such as precious metals (e.g., gold, silver and platinum) and copper.Various aspects and embodiments of the present invention, however, proveespecially advantageous in connection with the recovery of cobalt from apreprocessed cobalt bearing material. A preprocessed cobalt bearingmaterial may comprise a material that has been subjected to a priormetallurgical process. For example, a metallurgical process may resultin the formation of cobalt hydroxide Co(OH)₂. Cobalt hydroxide may beformed by combining a cobalt bearing material with magnesium oxide (MgO)and/or lime. It should be appreciated that a preprocessed cobalt bearingmaterial may contain various other constituents as impurities orcoprecipitates, such as copper, zinc, manganese and/or nickel. Invarious embodiments, cobalt bearing material 102 comprises cobalthydroxide. In various embodiments, cobalt bearing material 102 comprisescobalt hydroxide produced by addition of magnesium oxide to a materialcontaining cobalt ions. In various embodiments, cobalt bearing material102 comprises cobalt hydroxide produced by addition of lime to amaterial containing cobalt ions. In various embodiments, cobalt bearingmaterial 102 comprises cobalt hydroxide produced by addition of limeand/or magnesium oxide. Cobalt produced using magnesium oxide isgenerally considered of greater quality than cobalt produced using lime,though various factors, including reagent costs, may affect theselection of an appropriate cobalt bearing material.

With continued reference to FIG. 1, after cobalt bearing material 102has been suitably prepared, cobalt bearing material 102 may be subjectedto reactive process 104 to put cobalt in cobalt bearing material 102 ina condition for later cobalt recovery steps.

In accordance with various embodiments, reactive processing 104 maycomprise any type of reactive process that is capable of yielding cobaltin cobalt bearing material 102 in a condition to be subjected to latermetal recovery steps. For example, in various embodiments, reactiveprocessing 104 comprises a leaching operation. In various embodiments,reactive processing 104 yields cobalt bearing reactive processedmaterial 105, described in detail herein below.

Cobalt bearing reactive processed material 105 may be directed tofiltration 106. Filtration 106 may comprise any suitable filtrationprocess. For example, vacuum filters such as a bat filter may be used.In addition, pressure filters such as a plate and frame filter may beused.

Filtration 106 may separate the cobalt bearing reactive processedmaterial 105 into a solid phase and a liquid phase. The solid phase issent to primary leaching process 120. Primary leaching process 120 maycomprise a leaching process that is intended to liberate one or moremetals from a metal bearing material. For example, in variousembodiments, primary leaching process 120 comprises a leaching processthat tends to liberate copper from a copper bearing material. The liquidphase of cobalt bearing reactive processed material 105 comprisesfiltrate 107. Filtrate 107 is forwarded to conditioning 108.

In various embodiments, conditioning 108 comprises one or more chemicaland/or physical processing steps. The filtrate 107 may be conditioned toadjust the composition, component concentrations, solids content,volume, temperature, pressure, and/or other physical and/or chemicalparameters to desired values and thus to form a suitable copper-bearingsolution. Generally, a properly conditioned copper-bearing solution willcontain a relatively high concentration of soluble copper, for example,copper sulfate, in an acid solution and preferably will contain fewimpurities. Moreover, the conditions of the copper-bearing solutionpreferably are kept substantially constant to enhance the quality anduniformity of the copper product ultimately recovered. In variousembodiments, conditioning 108 comprises a solution extraction operation.

In various embodiments, conditioning 108 produces conditioned solution118 and conditioned solution 116. Conditioned solution 118 may beforwarded to precipitation and filtration 112.

Precipitation and filtration 112 may comprise a filtration processwherein a reagent is added to selectively precipitate cobalt.Precipitation and filtration 112 may comprise a precipitation thatincludes the use of a variety of precipitants, including, for example,calcium compounds such as gypsum (calcium sulfate), lime (calciumhydroxide and/or calcium oxide), calcium carbonate and milk of lime(certain preparations of calcium hydroxide). In various embodiments, anysuitable source of gypsum or lime may be used in precipitation andfiltration 112. For example, lime and gypsum may be added toprecipitation and filtration 112 to precipitate cobalt as cobalt gypsum(“CoGyp”). Precipitation and filtration 112 thus produces precipitatedcobalt 114. Precipitated cobalt 114 may be passed to reactive process104.

Conditioned solution 116 may be passed to further processing 110.Further processing 110 may comprise any metal recovery process, such asion exchange, electrowinning, solution extraction, carbon columnfiltering, and combinations thereof. Further processing may yield cobaltmetal.

As shown in metal recovery process 100, the connection to primaryleaching process 120 allows for greater efficiency and efficacy in therecovery of a primary metal. For example, a primary metal may becontained in Co MAT 102. As cobalt is further refined and recovered, theprimary metal may be separated from cobalt and recovered itself inanother process, such as primary leaching process 120.

With reference to FIG. 2, metal recovery process 200 is illustrated.Metal recovery process 200 contains certain steps found in metalrecovery process 100. Upstream bleed 206 is taken from the output offiltration 106. As described above, upstream bleed 206, which is locatedafter a filtration process, tends to decrease downstream solutionvolumes. Thus, downstream metal recovery processes may act on lowervolumes of solution than in previous systems. Accordingly, reagent costand plant equipment cost tends to be lessened. Moreover, upstream bleed206 allows for a reduction of impurities

Leach 202 may comprise leaching may be any method, process, or systemthat enables cobalt to be leached from cobalt bearing material 102.Typically, leaching utilizes acid to leach cobalt from cobalt bearingmaterial 102. Basic (i.e., caustic) leaches may be used, however. Forexample, leaching can employ a leaching apparatus such as for example, aheap leach, a vat leach, a tank leach, a simultaneous grind-leachapparatus, a pad leach, a leach vessel or any other leaching technology,known to those skilled in the art or hereafter developed, that is usefulfor leaching cobalt from cobalt bearing material 102.

In accordance with various embodiments, leaching may be conducted at anysuitable pressure, temperature, and/or oxygen content. Leaching canemploy one of a high temperature, a medium temperature, or a lowtemperature, combined with one of high pressure, or atmosphericpressure. Leaching may utilize conventional atmospheric or pressureleaching, for example, but not limited to, low, medium or hightemperature pressure leaching. As used herein, the term “pressureleaching” refers to cobalt recovery process in which material iscontacted with an acidic or a basic solution and oxygen under conditionsof elevated temperature and pressure. Medium or high temperaturepressure leaching processes which are generally thought of as thoseprocesses operating under acidic conditions at temperatures from about120° C. to about 190° C. or up to about 250° C.

Leach 202 is conducted in acid media under the addition of sulfurdioxide gas. Leach 202 may be performed under pressure and attemperatures above 25° C., though in various embodiments, leach 202 isconducted at atmospheric temperature and ambient temperature. Leach 202yields leachate 203 that is forwarded to filtration 106. Sulfur dioxideaddition acts to reduce cobalt III into cobalt II, which is more easilydissolved into solution.

Solution extraction 204 is configured to selectively extract impurities,as described in further detail herein. In various embodiments, solutionextraction 204 comprises a liquid-liquid extraction. During solutionextraction 204, impurities from the filtrate 205 may be loadedselectively into an organic phase in an extraction stage. Impurities mayinclude one or more of copper, zinc, manganese and nickel. In variousembodiments, the organic phase comprises an extracting agent, which mayalso be referred to as an extractant, to aid in transporting theimpurities to the organic phase. For example,Di-(2-ethylhexyl)phosphoric acid (D2EHPA) may be used as an extractingagent. Cobalt is retained in the aqueous phase and Zn, Mn, and Ca areloaded in the organic phase.

The organic phase from solution extraction 204 may be then subjected toone or more wash stages in which the loaded organic phase is contactedwith an aqueous phase in order to remove aqueous cobalt bearing solutiondroplets from the organic phase. However, in various embodiments, a washstage is not included. The organic phase may then be subject to asolvent stripping stage, wherein the impurities are transferred to anaqueous phase. For example, more acidic conditions may shift theequilibrium conditions to cause the impurities to migrate to the aqueousphase. The aqueous phase, which contains the impurities, may beprocessed in a suitable manner. The organic phase is thus purged ofimpurities and, in various embodiments, may be contacted again withliquids from liquid phase. Conditioned solution 118 thus comprisescobalt containing liquid from solution extraction 204.

Upstream bleed 206 comprises a portion of filtrate 205. Upstream bleed206 may be used to bleed a portion of filtrate 205 to precipitation andfiltration 112, thus bypassing solution extraction 204. Upstream bleed206 allows for the reduction of impurities from the circuit and for thereduction in process volumes in downstream processing. For example,leachate 203 from leach 202 may be of relatively low cobaltconcentration. Upstream bleed 206 provides a portion of the liquid phaseof leachate 203 to precipitation and filtration 112, allowing the cobaltto be precipitated and the cobalt-depleted liquid phase with theimpurities to be sent to elsewhere (e.g., to tails). Stated another way,upstream bleed 206 acts to reduce solution volumes, in turn reducing thevolume of solution that is subject to other metal recovery processes. Byreducing volume prior to other processing steps, the volume of solutionused in the other processing steps relative to the cobalt containedtherein is lower than in conventional systems. Accordingly, processequipment may be downsized as the equipment need not be sized toaccommodate a large volume of low cobalt concentration liquor. Thereduction in equipment size is also a cost savings over conventionalsystems on a per mass unit of cobalt recovered basis.

With reference to FIG. 3, metal recovery process 300 is illustrated.Metal recovery process 300 contains certain steps found in metalrecovery process 200, but FIG. 3 illustrates an embodiment includingcobalt precipitation and further primary metal recovery.

As discussed above, cobalt bearing material 102 may be produced inproximity to other metallurgical operations. For example, certain miningoperations recover more than one metal from an ore body. Certain orebodies comprise cobalt and copper, among other metals. Copper may beleached in a primary leaching operation. During the processing of theleachate from such a primary leaching operation, it may be beneficial tobegin cobalt recovery. For example, cobalt bearing solution 303 mayoriginate from primary metal recovery 304. In various embodiments,cobalt bearing solution 303 may comprise a raffinate from a solutionextraction process.

Cobalt bearing solution 303 may be forwarded to cobalt precipitation302. Cobalt precipitation 302 may comprise any process by which cobaltis precipitated out of solution using a precipitating agent. Aprecipitant or precipitating agent, used herein interchangeably, is anagent that, when added to a solution, causes at least a portion of asolute to precipitate. A variety of precipitating agents may be used toprecipitate metal values. Any agent that may precipitate a metal valuefrom an aqueous solution may be used as a precipitating agent.Precipitating agents may include various hydroxides and carbonates. Morespecifically, precipitating agents may include magnesium hydroxide,lime, magnesium oxide (also known in the art as magnesia), ammoniumhydroxide, potassium hydroxide, calcium carbonate, ammonium sulphate,sodium carbonate, magnesium carbonate, potassium, and sodium hydroxide.In an exemplary embodiment, any form of magnesium oxide may be used as aprecipitating agent. For example, forms of magnesium oxide include solidmagnesium oxide, calcined magnesium oxide and slurried, calcinedmagnesium oxide. Cobalt precipitation 302 may comprise multipleprecipitation steps performed in parallel or in series.

The use of one precipitant over another is determined based on a numberof factors. As discussed above, cobalt produced using magnesium oxide isgenerally considered of greater quality than cobalt produced using lime.Generally speaking, industrially produced cobalt hydroxide usingmagnesium is approximately 30%-45% pure, whereas industrially producedcobalt hydroxide using lime is approximately 10%-25% pure. Cobalthydroxide is a commercially marketable product, so the desired return oninvestment may be weighed using the present or predicted market price ofboth materials. Thus, it may be beneficial in operations that produceboth products to adjust the balance of the type and amount of cobalthydroxide that is recovered and the type and amount of cobalt hydroxidethat is marketed directly. Solids 301 from cobalt precipitation 302 maybe used as cobalt bearing material 102. Cobalt metal is obtained inelectrowinning 308.

Primary leach 120 may output a primary metal bearing solution 305 to beforwarded to primary metal recovery 304. Primary metal recovery 304 maycomprise one or more processes that tend to recover a primary metalvalue. For example, primary metal recovery 304 yields primary metalvalue 306.

With reference to FIG. 4, metal recovery process 400 is illustrated.Metal recovery process 400 contains certain steps found in metalrecovery process 300, but FIG. 4 illustrates an embodiment includingdual cobalt precipitations.

Leachate from a primary metal leach is subject to solution extraction,and the raffinate is subject to cobalt precipitation 402. Cobaltprecipitation 402 comprises the addition of a precipitating agent suchas magnesia, lime, and/or other precipitating agents to the raffinatesolution. The resultant slurry 403 that forms in cobalt precipitation402 is subject to cobalt leach 404.

Cobalt leach 404 is conducted in acid media under the addition of sulfurdioxide gas, though any suitable reducing agent may be used in lieu ofor with sulfur dioxide gas. Sulfur dioxide addition acts to reducecobalt III into cobalt II, which is readily dissolved into solution.Cobalt leach 404 may be performed under pressure and at temperaturesabove 25° C., though in various embodiments, cobalt leach 404 isconducted at atmospheric pressure and at a temperature of about 50° C.Cobalt leach 404 yields a leachate that is forwarded to filtration 408.Acid may also be added to cobalt leach 404 from time to time.

Filtration 408 separates the slurry output of cobalt leach 404 into asolid phase and a liquid phase. Filtration 408 comprises filtering theslurry output of cobalt leach 404 in the presence of gypsum. It has beenfound that gypsum added via lime as a precipitant in one of the processstages tends to act as a suitable filtering aid, in addition toproviding various other benefits.

Solid phase output 430 of filtration 408 is sent to a primary leachingprocess. Primary leaching process comprises a leaching process that isintended to liberate one or more metals from a metal bearing material.For example, in various embodiments, a primary leaching processcomprises a leaching process to liberate copper and cobalt from a metalbearing material that comprises copper and cobalt

A first portion of the liquid phase output of filtration 408 is bled asbleed 412 to precipitation and filtration 410. A second portion of theliquid phase output of filtration 408 is forwarded to Zn/Mn/Ca SX 406.Zn/Mn/Ca SX 406 comprises a solution extraction process that removes,among other things, Zn, Mn, and Ca from the liquid portion output offiltration 408. The aqueous liquid portion of the liquid portion outputof filtration 408 may be contacted with an organic solution and anextractant.

Zn/Mn/Ca SX 406 uses D2EHPA as an extractant. After impurities arebrought in the organic phase, the organic phase may be washed withwater, though in various embodiments the organic phase is not washed.The organic phase may be scrubbed with dilute sulfuric acid to strip anycobalt that was extracted from the aqueous phase. After scrubbing, thedilute sulfuric acid, which now contains cobalt scrubbed from theorganic phase, may be sent back to precipitation and filtration 112 viascrubbed cobalt solution 470. The organic phase may be stripped with anadditional aqueous phase to bring impurities to the aqueous phase. Theadditional aqueous phase may be suitably treated. Acid for stripping theorganic phase may be generated from other processes, for example,raffinate from undivided electrowinning 422 or other acidic streams fromthe primary metal recovery process. The aqueous phase Zn/Mn/Ca SX 406produces may be referred to as extracted cobalt bearing solution 409.

A portion of extracted cobalt bearing solution 409 is forwarded toprecipitation and filtration 410. Precipitation and filtration 410comprises a filtration process wherein a reagent is added to selectivelyprecipitate cobalt. Precipitation and filtration 410 may comprise aprecipitation that includes the use of a variety of precipitants,including, for example, calcium, lime (calcium hydroxide and/or calciumoxide), calcium carbonate and milk of lime (certain preparations ofcalcium hydroxide). In various embodiments, any suitable source ofgypsum or lime may be used in precipitation and filtration 410. Forexample, lime may be added to precipitation and filtration 410 toprecipitate cobalt as cobalt gypsum (“CoGyp”). Precipitation andfiltration 410 thus produces precipitated cobalt 405. Precipitatedcobalt 405 may be passed to leach 404.

A portion of extracted cobalt bearing solution 409 is then subjected toorganic polishing 414. Organic polishing 414 comprises a filtration ofextracted cobalt bearing solution 409 in a carbon column. A carboncolumn may comprise any suitable carbon media, such as, for example,activated charcoal, powdered activated carbon or granulated activatedcarbon. Carbon media may adsorb various impurities from extracted cobaltbearing solution 409. For example, carbon media may adsorb organiccompounds from extracted cobalt bearing solution 409. Carbon media issuited for adsorption due to its high surface area, among otherproperties. In that regard, other media may be used in organic polishing414 that are suitable for adsorbing or absorbing organic compounds.Carbon media may periodically be regenerated or replaced to maintainappropriate adsorbing performance. Organic polishing 414 producespolished cobalt bearing solution 411.

Polished cobalt bearing solution 411 may be forwarded to copper ionexchange (Cu IX) 416. Copper may be present at relatively lowconcentrations in polished cobalt bearing solution 411. Copper presentin polished cobalt bearing solution 411 may exist as copper I and/orcopper II. Cu IX 416 may be used to remove copper. Copper removed by CuIX 416 may be in either metal or ionic form. Ion exchange may beaccomplished in any suitable manner. For example, polished cobaltbearing solution 411 may be contacted with a surface or membranecontaining ions. A surface or membrane in an ion exchange step may becomprised of a synthetic resin, a polymer, or any other suitablematerial. In various embodiments, for example, LEWATIT MONOPLUS TP207resin, made by Lanxess of Birmingham, N.J. USA, is used. In furtherembodiments, PUROLITE S950 resin, made by Purolite, Inc. of 150 MonumentRoad, Bala Cynwyd, Pa. 19004, USA is used. Copper from cobalt bearingsolution 411 may be exchanged with ions present on the surface ormembrane, leaving copper present on the surface or membrane. Themembrane or surface may be washed periodically to remove the adheredcopper and increase efficacy of the ion exchange step. During suchperiodic washing, acid or other media may be contacted with the membraneor surface to remove the deposited copper ions. The acid or other mediamay be recycled into a primary leaching process to recover the copperions washed off the membrane or surface. Cu IX 416 produces exchangedcobalt bearing solution 413. Copper removal could also be done with asuitable organic extractant using liquid extraction, although in variousembodiments, solvent extraction is not used for removing copper.

Exchanged cobalt bearing solution 413 is subjected to organic polishing418. Organic polishing 418 may be conducted in the same or similarmanner as organic polishing 414. For example, exchanged cobalt bearingsolution 413 may be contacted with a carbon column to further removeimpurities, such as organic compounds. Organic polishing 418 producespolished cobalt bearing solution 415.

Polished cobalt bearing solution 415 may be subjected to nickel ionexchange (Ni IX) 420. NiIX 420 may be accomplished in any suitablemanner. For example, polished cobalt bearing solution 415 may becontacted with a surface or membrane containing ions. A surface ormembrane in an ion exchange step may be comprised of a synthetic resin,a polymer, or any other suitable material. In various embodiments, forexample, DOWEX M4195 resin is used. DOWEX M4195 is made by the DowChemical Company, Dow Water Solutions, Customer Information Center, P.O.Box 1206, Midland, Mich. 48642-1206. In further embodiments, forexample, DOWEX XUS43605 resin is used. DOWEX XUS43605 is made by the DowChemical Company, Dow Water Solutions, Customer Information Center, P.O.Box 1206, Midland, Mich. 48642-1206. Nickel from polished cobalt bearingsolution 415 may be exchanged with ions present on the surface ormembrane, leaving nickel present on the surface or membrane. In variousembodiments, a portion of the cobalt in polished cobalt bearing solution415 may also become bound to the surface or membrane. NiIX 420 producespurified cobalt bearing solution 417.

The membrane or surface may be washed periodically to remove the adheredcobalt and increase efficacy of the ion exchange step. For example, CoElution 424 comprises a regeneration or purging of the membrane orsurface of NiIX 420 to remove cobalt that may have adhered to themembrane or surface. In that regard, Co Elution 424 may comprisecontacting an elution medium, such as an acid medium, with the membraneor surface. The elution medium may be conducted to leach 404 to improvecobalt recovery.

The membrane or surface may be washed periodically to remove the adherednickel and increase efficacy of the ion exchange step. Ni Elution 424comprises a regeneration or purging of the membrane or surface of NiIX420 to remove nickel that may have adhered to the membrane or surface.In that regard, Ni Elution 424 may comprise contacting an elutionmedium, such as an acid medium, with the membrane or surface. Theelution medium may be conducted to tails via neutralization 428.Neutralization 428 may include the addition of lime or other agent toadjust the pH of the tails.

Purified cobalt bearing solution 417 may be forwarded to electrowinningcell 422. Electrowinning cell 422 yields a cobalt metal cathode product.As those skilled in the art are aware, a variety of methods andapparatus are available for the electrowinning of cobalt and other metalvalues, any of which may be suitable for use in accordance with thepresent invention, provided the requisite process parameters for thechosen method or apparatus are satisfied.

In various embodiments, electrowinning may be performed inelectrowinning cell 422 such that the anodes and cathodes are notseparated into compartments. In such embodiments, the anodes andcathodes are placed in the same media without a barrier and electricalcurrent is applied. For example, electrowinning cell 422 may comprise acathode compartment and an anode compartment. Metal values, such ascobalt, may evolve at the cathode. Manganese, among others species, mayevolve at the anode. It has been found that electrowinning in undividedcompartment is advantageous where the electrowinning is done in closeproximity to a primary metal recovery operation.

With reference to FIG. 5, metal recovery process 500 is illustrated.Metal recovery process 500 is conducted not in close proximity to aprimary metal recovery process. In this regard, various output streamsmay be sent to tails instead of to a primary metal recovery process and,for example, to a primary metal leaching process. However, recoveryprocess 500 benefits from the use of divided compartment electrowinning,as further discussed below.

Metal recovery process 500 comprises subjecting cobalt bearing material(“Co MAT”) 502 to leach 504, filtration 507, and solution extraction513. At least a portion of the tails of filtration 507 may proceed totails 522. Metal recovery process 500 comprises divided compartmentelectrowinning 518.

Cobalt bearing material 502 may be an ore (cobaltite, heterogenite(CoOOH), erythrite, glaucodot, skutterudite, other cobalt containingores, and mixtures of cobalt containing ores with ores bearing othermetal values), a concentrate, a process residue, an impure metal salt, apreprocessed cobalt bearing material, combinations thereof, or any othermaterial from which cobalt values are present. Cobalt, whether in metalor ionic form, may be recovered from cobalt bearing material 502 inaccordance with various embodiments of the present invention. In variousembodiments, cobalt bearing material 502 contains other metal values,such as precious metals (e.g., gold, silver and platinum) and copper.Various aspects and embodiments of the present invention, however, proveespecially advantageous in connection with the recovery of cobalt from apreprocessed cobalt bearing material. A preprocessed cobalt bearingmaterial may comprise a material that has been subjected to a priormetallurgical process. For example, a metallurgical process may resultin the formation of cobalt hydroxide (Co(OH)₂). Cobalt hydroxide may beformed by combining a cobalt bearing material with magnesium oxide (MgO)and/or lime. It should be appreciated that a preprocessed cobalt bearingmaterial may contain various other constituents as impurities orcoprecipitates, such as copper, zinc, and/or nickel. In variousembodiments, cobalt bearing material 502 comprises cobalt hydroxide. Invarious embodiments, cobalt bearing material 502 comprises cobalthydroxide produced by addition of magnesium oxide to a materialcontaining cobalt ions. In various embodiments, cobalt bearing material502 comprises cobalt hydroxide produced by addition of lime to amaterial containing cobalt ions. In various embodiments, cobalt bearingmaterial 502 comprises cobalt hydroxide produced by addition of limeand/or magnesium oxide. Cobalt produced using magnesium oxide isgenerally considered of greater quality than cobalt produced using lime,though various factors, including reagent costs, may affect theselection of an appropriate cobalt bearing material.

In accordance with various embodiments, leach 504 may comprise any typeof leaching process that is capable of yielding received cobalt 503 to acondition to be subjected to later metal recovery steps. In variousembodiments, leach 504 yields cobalt bearing leachate 506, described indetail herein below.

Leachate 506 may be directed to filtration 507. Filtration 507 maycomprise any suitable filtration process. For example, vacuum filterssuch as a belt filter or disc filter may be used. In addition, pressurefilters such as a plate and frame filter may be used.

Filtration 507 may separate the leachate 506 into a solid phase and aliquid phase. The solid phase is sent to tails 522. Tails 522 may betreated (e.g., neutralized) and processed in any suitable manner. Theliquid phase of leachate 506 comprises liquid leachate 508. Liquidleachate 508 is forwarded to solution extraction 513.

In various embodiments, solution extraction 513 comprises a solutionextraction process. Solution extraction 513 is configured to selectivelyextract impurities, as described in further detail herein. In variousembodiments, solution extraction 513 comprises a liquid-liquidextraction. During solution extraction 513, cobalt (e.g., ionic cobalt)from the liquids phase may be loaded selectively into an organic phasein an extraction stage, wherein the organic phase comprises anextracting agent, which may also be referred to as an extractant. Forexample, Di-(2-ethylhexyl)phosphoric acid (D2EHPA) may be used as anextracting agent. Cobalt is retained in the aqueous phase and Zn, Mn,and Ca are loaded in the organic phase.

The organic phase from solution extraction 513 may be then subjected toone or more wash stages and/or scrub stages in which the loaded organicphase is contacted with an aqueous phase in order to removeentrained/extracted aqueous solution from the organic phase. The washedorganic phase may then be subject to a solvent stripping stage, whereinthe cobalt is transferred to an aqueous phase. For example, more acidicconditions may shift the equilibrium conditions to cause the cobalt tomigrate to the aqueous phase. Loaded aqueous streams 512 and 514 thuscomprise cobalt containing liquid from solution extraction 513.

Loaded aqueous stream 512 may be forwarded to precipitation andfiltration 511, to precipitate any cobalt that was stripped from theorganic phase in the wash/scrub stage.

Precipitation and filtration 511 may comprise a filtration processwherein a reagent is added to selectively precipitate cobalt.Precipitation and filtration 511 may comprise a precipitation thatincludes the use of a variety of precipitants, including, for example,calcium compounds such as gypsum (calcium sulfate), lime (calciumhydroxide and/or calcium oxide), calcium carbonate and milk of lime(certain preparations of calcium hydroxide). In various embodiments, anysuitable source of gypsum or lime may be used in precipitation andfiltration 511. For example, lime and gypsum may be added toprecipitation and filtration 511 to precipitate cobalt as cobalt gypsum(“CoGyp”). Precipitation and filtration 511 thus produces precipitatedcobalt 510. Precipitated cobalt 510 may be passed to leach 504.

Loaded aqueous stream 514 may be passed to further processing 516.Further processing 516 may comprise any metal recovery process, such asion exchange, electrowinning, solution extraction, carbon columnfiltering, and combinations thereof. Processed cobalt bearing material517 is forwarded to compartmentalized electrode electrowinning 518.Processed cobalt bearing material 517 may yield cobalt metal. Forexample, processed cobalt bearing material 517 may compriseelectrowinning cobalt using a compartmentalized (e.g., bagged) electrodeprocess.

Bagged electrodes, such as bagged anodes, are advantageously employed toenhance cobalt recovery. Typical bagged electrode processes tend tobenefit from enhanced monitoring and care. Thus, bagged electrodeprocesses may benefit from being conducted not in close proximity to aprimary metal recovery process so that appropriate skilled personnel mayproperly maintain process conditions.

Upstream bleed 509 comprises a portion of filtrate 508. Upstream bleed509 may be used to bleed a portion of filtrate 508 to precipitation andfiltration 511, thus bypassing solution extraction 513. Upstream bleed509 acts as a bleed of impurities such as MgSO₄ and Na₂SO₄ from thecircuit and allows for the reduction in process volumes in downstreamprocessing, whose benefits are described elsewhere herein.

With reference to FIG. 6, metal recovery process 600 is illustrated.Metal recovery process 600 operates not in close proximity to a primarymetal recovery process. CHIP 602 may comprise a cobalt hydroxideproduct, for example, that which may be obtained by precipitating cobaltfrom an aqueous solution using a precipitating agent. CHIP 602 may beobtained commercially. CHIP 602 may be mixed with an aqueous solution,such as acid, and subject cobalt leach 604.

Cobalt leach 604 is conducted in acid media under the addition of sulfurdioxide gas, though any suitable reducing agent may be used in lieu ofor with sulfur dioxide gas. Cobalt leach 604 may be performed underpressure and at temperatures above 25° C., though in variousembodiments, cobalt leach 604 is conducted at atmospheric temperatureand ambient temperature. Cobalt leach 604 yields a leachate that isforwarded to filtration 608. Sulfur dioxide addition acts to reducecobalt Ill into cobalt II, which is readily dissolved into solution.Acid may also be added to cobalt leach 604 from time to time.

Filtration 608 separates the slurry output of cobalt leach 604 into asolid phase and a liquid phase. Filtration 608 comprises filtering theslurry output of cobalt leach 604 in the presence of gypsum. It has beenfound that gypsum acts as a suitable filtering aid, in addition toproviding various other benefits.

Solid phase output 630 of filtration 608 is sent to neutralization/tails628. Neutralization/tails 628 may comprise an addition of lime or otheragent to chemically adjust the pH of the tails prior to furtherprocessing of the tails.

A first portion of the liquid phase output of filtration 608 is bled asbleed 612 to precipitation and filtration 610. A second portion of theliquid phase output of filtration 608 is forwarded to Zn/Mn/Ca SX 606.Zn/Mn/Ca SX 606 comprises a solution extraction process that removes,among other things, Zn, Mn, and Ca from the liquid portion output offiltration 608. The aqueous liquid portion of the liquid portion outputof filtration 608 may be contacted with an organic solution and anextractant.

Zn/Mn/Ca SX 606 uses D2EHPA as an extractant. After cobalt is brought inthe organic phase, the organic phase may be washed with water, though invarious embodiments the organic phase is not washed. The organic phasemay be stripped with an aqueous phase to bring cobalt to the aqueousphase. Acid for stripping the organic phase may be generated from otherprocesses, for example, raffinate from undivided electrowinning 622 orother acidic streams from the primary metal recovery process. Theaqueous phase Zn/Mn/Ca SX 606 produces may be referred to as extractedcobalt bearing solution 609.

Portion 607 of extracted cobalt bearing solution 609 is forwarded toprecipitation and filtration 610. Precipitation and filtration 610comprises a filtration process wherein a reagent is added to selectivelyprecipitate cobalt. Precipitation and filtration 610 may comprise aprecipitation that includes the use of a variety of precipitants,including, for example, calcium compounds such as gypsum (calciumsulfate), lime (calcium hydroxide and/or calcium oxide), calciumcarbonate and milk of lime (certain preparations of calcium hydroxide).In various embodiments, any suitable source of gypsum or lime may beused in precipitation and filtration 610. For example, lime and gypsummay be added to precipitation and filtration 610 to precipitate cobaltas cobalt gypsum (“CoGyp”). Precipitation and filtration 610 thusproduces precipitated cobalt 605. Precipitated cobalt 605 may be passedto leach 604.

A portion of extracted cobalt bearing solution 609 is then subjected toorganic polishing 614. Organic polishing 614 comprises a filtration ofextracted cobalt bearing solution 609 in a carbon column. A carboncolumn may comprise any suitable carbon media, such as, for example,activated charcoal, powdered activated carbon or granulated activatedcarbon. Carbon media may adsorb various impurities from extracted cobaltbearing solution 609. For example, carbon media may adsorb organiccompounds from extracted cobalt bearing solution 609. Carbon media issuited for adsorption due to its high surface area, among otherproperties. In that regard, other media may be used in organic polishing614 that are suitable for adsorbing or absorbing organic compounds.Carbon media may periodically be regenerated or replaced to maintainappropriate adsorbing performance. Organic polishing 614 producespolished cobalt bearing solution 611.

Polished cobalt bearing solution 611 may be forwarded to copper ionexchange (Cu IX) 616. Copper may be present at relatively lowconcentrations in polished cobalt bearing solution 611. Copper presentin polished cobalt bearing solution 611 may exist as copper I and/orcopper II. Cu IX 616 may be used to remove copper. Copper removed by CuIX 616 may be in either metal or ionic form. Ion exchange may beaccomplished in any suitable manner. For example, polished cobaltbearing solution 611 may be contacted with a surface or membranecontaining ions. A surface or membrane in an ion exchange step may becomprised of a synthetic resin, a polymer, or any other suitablematerial. In various embodiments, for example, LEWATIT MONOPLUS TP207resin, made by Lanxess of Birmingham, N.J. USA, is used. In furtherembodiments, PUJROITE S950 resin, made by Purolite, Inc. of 150 MonumentRoad, Bala Cynwyd, Pa. 19004, USA is used. Copper from cobalt bearingsolution 611 may be exchanged with ions present on the surface ormembrane, leaving copper present on the surface or membrane. Themembrane or surface may be washed periodically to remove the adheredcopper and increase efficacy of the ion exchange step. During suchperiodic washing, acid or other media may be contacted with the membraneor surface to remove the deposited copper ions. The acid or other mediamay be recycled into a primary leaching process to recover the copperions washed off the membrane or surface. Cu IX 616 produces exchangedcobalt bearing solution 613.

Exchanged cobalt bearing solution 613 is subjected to organic polishing618. Organic polishing 618 may be conducted in the same or similarmanner as organic polishing 614. For example, exchanged cobalt bearingsolution 613 may be contacted with a carbon column to further removeimpurities, such as organic compounds. Organic polishing 618 producespolished cobalt bearing solution 615.

Polished cobalt bearing solution 615 may be subjected to nickel ionexchange (Ni IX) 620. NiIX 620 may be accomplished in any suitablemanner. For example, polished cobalt bearing solution 615 may becontacted with a surface or membrane containing ions. A surface ormembrane in an ion exchange step may be comprised of a synthetic resin,a polymer, or any other suitable material. In various embodiments, forexample, DOWEX M4195 resin is used. DOWEX M4195 is made by the DowChemical Company, Dow Water Solutions, Customer Information Center, P.O.Box 1206, Midland, Mich. 48642-1206. In further embodiments, forexample, DOWEX XUS43605 resin is used. DOWEX XUS43605 is made by the DowChemical Company, Dow Water Solutions, Customer Information Center, P.O.Box 1206, Midland, Mich. 48642-1206. Nickel from polished cobalt bearingsolution 615 may be exchanged with ions present on the surface ormembrane, leaving nickel present on the surface or membrane. In variousembodiments, a portion of the cobalt in polished cobalt bearing solution615 may also become bound to the surface or membrane. NiIX 620 producespurified cobalt bearing solution 617.

The membrane or surface may be washed periodically to remove the adheredcobalt and increase efficacy of the ion exchange step. For example, CoElution 624 comprises a regeneration or purging of the membrane orsurface of NiIX 620 to remove cobalt that may have adhered to themembrane or surface. In that regard, Co Elution 624 may comprisecontacting an elution medium, such as an acid medium, with the membraneor surface. The elution medium may be conducted to leach 604 to improvecobalt recovery.

The membrane or surface may be washed periodically to remove the adherednickel and increase efficacy of the ion exchange step. Ni Elution 626comprises a regeneration or purging of the membrane or surface of NiIX620 to remove nickel that may have adhered to the membrane or surface.In that regard, Ni Elution 626 may comprise contacting an elutionmedium, such as an acid medium, with the membrane or surface. Theelution medium may be conducted to tails via neutralization/tails 628.

Purified cobalt bearing solution 617 may be forwarded to electrowinningcell 622. Electrowinning cell 622 yields a cobalt metal cathode product.As those skilled in the art are aware, a variety of methods andapparatus are available for the electrowinning of cobalt and other metalvalues, any of which may be suitable for use in accordance with thepresent invention, provided the requisite process parameters for thechosen method or apparatus are satisfied.

In various embodiments, electrowinning may be performed inelectrowinning cell 622 such that the anodes and cathodes are housed inseparate compartments. For example, electrowinning cell 622 maycomprises a cathode compartment and an anode compartment.

Compartments may be formed by the placement of a bag or other barrier,whether permeable or semi-permeable, around or partially around one ormore of the anodes and cathodes. For example, a bag may be placed aroundall or a portion of an anode. The electrolyte is thus divided intoanolyte and catholyte. A bag that at least partially encloses the anodemay be semi-permeable to anolyte. In that regard, anolyte may bewithdrawn from within the semi-permeable anode bag by the slightnegative pressure created from an anolyte gas scrubber fan, thusavoiding the generation of acid mist within the electrowinningtankhouse. Bagged anodes may tend to prevent contact between the anodeand cathode. Various anodes and anode coatings may be susceptible toshort circuiting, thus it is beneficial to create barriers to preventsuch short circuiting.

Cobalt metal may evolve at the cathode. Manganese, among others species,may evolve at the anode. Manganese and other species from the anode maybe forwarded to a leach or other metal recovery processing operation.Lean electrolyte from the anode compartment may be forwarded to leach604.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. However, thebenefits, advantages, solutions to problems, and any element orcombination of elements that may cause any benefit, advantage, orsolution to occur or become more pronounced are not to be construed ascritical, required, or essential features or elements of any or all theclaims or the invention. Many changes and modifications within the scopeof the instant invention may be made without departing from the spiritthereof, and the invention includes all such modifications.Corresponding structures, materials, acts, and equivalents of allelements in the claims below are intended to include any structure,material, or acts for performing the functions in combination with otherclaim elements as specifically claimed. The scope of the inventionshould be determined by the appended claims and their legal equivalents,rather than by the examples given above.

1. A method comprising: leaching a cobalt bearing material to form aslurry; filtering the slurry to yield solids and a cobalt bearing liquidphase; and forwarding the solids to a second leaching operation.
 2. Themethod of claim 1, wherein the second leaching operation is a copperleaching operation.
 3. The method of claim 1, wherein the cobalt bearingmaterial comprises cobalt hydroxide.
 4. The method of claim 3, whereinthe cobalt hydroxide is formed by precipitating cobalt II with magnesia.5. The method of claim 4, wherein the cobalt hydroxide is formed byprecipitating cobalt II with lime.
 6. The method of claim 1, wherein theleaching comprises addition of sulfur dioxide.
 7. The method of claim 1,further comprising: performing a solution extraction of the cobaltbearing liquid phase to yield a purified cobalt bearing liquid phase;subjecting the purified cobalt bearing liquid phase to a copper ionexchange using a copper selective ion exchange resin.
 8. The method ofclaim 7, further comprising purging the copper selective ion exchangeresin of copper with an elution liquid.
 9. The method of claim 8,recycling the elution liquid to a copper leaching operation.
 10. Themethod of claim 1, further comprising electrowinning cobalt metal from afirst portion of the purified cobalt bearing liquid phase.
 11. A methodcomprising: adding magnesia to a cobalt bearing material to form a firstslurry; separating the first slurry into a saleable solid product and aliquid phase; adding lime to the liquid phase to form a second slurry;and separating the second slurry into a solid product and a liquidphase.
 12. The method of claim 11, further comprising leaching a portionof the saleable solid product and a portion of the solid product to forma leached slurry.
 13. The method of claim 12, further comprising:filtering the leached slurry to yield a cobalt bearing liquid phase;bleeding a first portion of the cobalt bearing liquid phase to a cobaltgypsum precipitation process.
 14. The method of claim 13, furthercomprising: performing a solution extraction of a second portion of thecobalt bearing liquid phase to yield a purified cobalt bearing liquidphase; precipitating cobalt gypsum by adding lime to a first portion ofthe purified cobalt bearing liquid phase in the cobalt gypsumprecipitation process.
 15. The method of claim 14, further comprisingrecycling the cobalt gypsum to the leaching.
 16. The method of claim 15,further comprising subjecting a second portion of the purified cobaltbearing liquid phase to an additional conditioning step to yield aconditioned cobalt bearing liquid.
 17. The method of claim 16, furthercomprising electrowinning cobalt metal from a first portion of theconditioned cobalt bearing liquid.
 18. The method of claim 17, whereinthe electrowinning comprises a bagged anode process.
 19. The method ofclaim 11, wherein the electrowinning comprises a free anode process. 20.The method of claim 11, wherein the electrowinning comprises depositingcobalt metal rounds on a masked cathode.